This uses an array of file names that match up with the array of checkboxes to avoid the goofy bunch of Call()s you had.

The percentage in the progress bar here is based on simple file count. You can update it to use file sizes copied / total file size.

Note that the progress is not updated during each actual file copy, just before/after each copy. There are more advanced techniques to use a File System Object (FSO) and get a file copy with progress. Search for examples on the forum if you fell ready to go there.